com.gemstone.gemfire.internal.memcached.commands.ReplaceCommand Maven / Gradle / Ivy

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/*
 * Copyright (c) 2010-2015 Pivotal Software, Inc. All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License"); you
 * may not use this file except in compliance with the License. You
 * may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
 * implied. See the License for the specific language governing
 * permissions and limitations under the License. See accompanying
 * LICENSE file.
 */
package com.gemstone.gemfire.internal.memcached.commands;

import java.nio.ByteBuffer;

import com.gemstone.gemfire.cache.Cache;
import com.gemstone.gemfire.cache.Region;
import com.gemstone.gemfire.internal.memcached.Reply;
import com.gemstone.gemfire.internal.memcached.ResponseStatus;
import com.gemstone.gemfire.internal.memcached.ValueWrapper;

/**
 * general format of the command is:

 * 
 * <command name> <key> <flags> <exptime> <bytes> [noreply]\r\n
 * 

 * 
 * "replace" means "store this data, but only if the server *does*
 * already hold data for this key".
 * 
 * @author Swapnil Bawaskar
 */
public class ReplaceCommand extends StorageCommand {

  @Override
  public ByteBuffer processStorageCommand(String key, byte[] value, int flags, Cache cache) {
    Region r = getMemcachedRegion(cache);
    Object oldVal = r.replace(key, ValueWrapper.getWrappedValue(value, flags));
    String reply = null;
    if (oldVal == null) {
      reply = Reply.NOT_STORED.toString();
    } else {
      reply = Reply.STORED.toString();
    }
    return asciiCharset.encode(reply);
  }

  @Override
  public ByteBuffer processBinaryStorageCommand(Object key, byte[] value, long cas,
      int flags, Cache cache, ByteBuffer response) {
    Region r = getMemcachedRegion(cache);
    ValueWrapper val = ValueWrapper.getWrappedValue(value, flags);
    boolean success = false;
    
    if (cas != 0L) {
      ValueWrapper expected = ValueWrapper.getDummyValue(cas);
      success = r.replace(key, expected, val);
    } else {
      success = r.replace(key, val) == null;
    }
    
    if (getLogger().fineEnabled()) {
      getLogger().fine("replace:key:"+key+" cas:"+cas+" success:"+success);
    }
    
    // set status
    if (success) {
      if (isQuiet()) {
        return null;
      }
      response.putShort(POSITION_RESPONSE_STATUS, ResponseStatus.KEY_EXISTS.asShort());
      response.putLong(POSITION_CAS, cas);
    } else {
      response.putShort(POSITION_RESPONSE_STATUS, ResponseStatus.NO_ERROR.asShort());
      // set CAS
      response.putLong(POSITION_CAS, val.getVersion());
    }
    return response;
  }

  /**
   * Overridden by Q command
   */
  protected boolean isQuiet() {
    return false;
  }
}